Why is it risky?
Lavender essential oil contains linalool and linalyl acetate, compounds with relaxing properties in humans but with hepatotoxic potential in cats due to impaired glucuronidation. Risk from lavender oil is lower than tea tree or eucalyptus but not negligible. Concentrated lavender oil should not be applied to cats or diffused in high concentrations in cat-occupied rooms. The dried lavender plant carries much lower risk than the concentrated oil.
Affected Systems
Nervous · Liver · Respiratory
Symptoms
Nausea, drooling, vomiting, lethargy. Concentrated or prolonged exposure: respiratory irritation, hepatic stress.
What To Do
Topical concentrated oil exposure: wash with mild soap and water. Symptomatic: vet visit.
Notes
The lavender plant (Lavandula angustifolia) and the concentrated essential oil are meaningfully different risk levels. ASPCA lists the plant as mildly toxic (mild GI upset from ingestion); the oil is a more concentrated source of the same compounds. Lavender-scented household products in normal use carry very low risk, the concern is with undiluted or concentrated formulations.
Sources
→ ASPCA Animal Poison Control Center — aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/lavender
→ Pet Poison Helpline — petpoisonhelpline.com
→ International Cat Care — icatcare.org